Apparatus for continuous solvent extraction and method thereof



Aug, 1-, 1933. w FLUMERFELT 1,920,499

APPARATUS FOR CONTINUOUS SOLVENT EXTRPLCTION AND METHOD THEREOF Filed Feb..4, 1931. 3 Sheets-Sheet 1 1 Aug. 1, IQBa. w. E. FLUMERFELT APPARATUS FOR CONTINUOUS SOLVENT EXTRACTION AND METHOD THEREOF Filed Feb. 4, 1931 5 Sheets-Sheet 2 Aug. 1, 1933- w. E. FLUMERFELT 1,920,499

APPARATUS FOR CONTINUOUS SOLVENT EXTRACTION AND METHOD THEREOF Filed Feb. 4, 1931 '5 Sheets-Sheet 3 Patented Aug. 1, 1933 TES UNITED .STA

APPARATUS FOR CONTINUOUS SOLVENT EXTRACTION AND METHOD THEREOF Walter E. Flumerfelt, Dallas Center, Iowa Application February 4, 1931. Serial No. 513,368

7 Claims.

My present invention has to do with an apparatus for carrying on continuous solvent extraction.

My apparatus can be used for carrying on a complete method or process for the extraction of various materials from animal, vegetable, mineral and chemical sources by use of liquid solvents and particularly for the extraction of fats, oils and allied substances by use of volatile solvent and the extraction of protein portions from parent sources by the use of suitable chemical solvents.

For convenience of description i refer frequently in my explanation to the use of the apparatus for extracting oleaginous materials from soy beans, but of course; do not want to limit myself to the use with this particular parent material, but use it as an illustration for extraction with volatile solvents.

Proper and efiective extraction of fats, oils and allied substances by volatile solvents necessitates unusual perfection in both. design and operation of equipment. Among the objects of my invention, it is my purpose to provide an apparatus having parts so constructed and arranged that the solvent extraction may be carried out with a minim oi loss and rislrs from escaping valu able solvent: 1

It is my purpose therefore to provide an apparatus having parts so constructed and arranged as to reduce loss and risit from escaping valuable solvents to a minimum and which will provide proper safety precautions and means.

Another object is to provide such an apparatus so constructed as to insure adequate permeation of the parent material by the solvent used, and to efiect maximum concentration of solvent with extractable substances, and to insure that the residue of parent material will contain the minimum of extractable substance when it leaves the extraction chamber.

Still another purpose is to provide an apparatus of this kind by which the separation of solvent and oil mixture from fine particles of the parent material may be emciently and, completely eifected; also by which there will be insured a complete recovery of errant fine particles to the residue body to which it belongs.

Another purpose is to provide an apparatus by which the transfer of extracted material from zone to zone of the apparatus may be accomplished without loss of motion, heat or solvent.

Still another object is to provide an apparatus by which the extracted residue may be properly dried to insure freedom from lingering traces of solvent.

An additional object is to provide an apparatus so constructed and arranged as to provide sure and effective means for isolating one part of the equipment from its adjacent parts for repairs or in cases of emergency.

Another object is to provide a method by which all the desirable results above mentioned may be conveniently and eificiently carried on.

Still a further object is to provide an apparatus and a method by which the solvent extraction can be continuously carried on.

With these and other objects in View, my in-v vention consists in the construction, arrangement and combination of the various parts of my apparatus and in the practice of my method, whereby the objects contemplated are attained as hereinafter more fully set forth, pointed out in my claims, and illustrated in the accompanying drawings, inwhich:

Figure 1 shows a vertical, sectional view through a part of an apparatus embodying my invention and with which my method may be practiced.

Figure 2 is a vertical, sectional view taken on the line 2-2 of Figure 1. V,

Figure 3 is a vertical sectional View of a portion of the egress conveyor from the main extraction chamber and above the solvent level.

Figure 4 is a vertical, sectional view of another part of the apparatus constituting the primary drier, parts being broken away.

Figure 8 is a detail, vertical sectional view of a modified form of a primary drier.

I will now explain the construction of my improved solvent extraction apparatus and in connection therewith outline the steps of the method.

InFigure 1, I have used the reference numeral shaft 21 joumaled in suitable bearings.

Preferably the raw material passes through a short pipe or the like 11. erahly mount a slide valve 12 supported in suitable guides 13 and having a projecting threaded rod-like member 14. Connected with the casing and mounted on the rod-like member 14 is an adjusting nut 15. This valve may be of any suitable construction for the purpose of regulating ingress of material.

Material is discharged from the pipe 11 into a specially designed screw conveyor which will not be described.

Screw conveyor One problem that is faced in carrying out my method of extraction is that of preventing the ,escape of volatiles. I solve this'problem by providing practical mechanical means for forming a plug or pack of the material being handled for preventing loss of the volatile vapors.

In the conveyor shown at the left-hand part of Figure 1, I have used standard smooth bore pipe 16 and Ts 17 to house a spiral screw of which there are sections 18 and 20 mounted on the On the shaft 21 between the spiral screw sections 18 and 20, there is provided a compacting element in the form of anenlargement 19 elliptical in longitudinalcross section so arranged as to reduce the inner cross sectional area of the conveyor housing member 16 as shown in Figure 1.

Thus when the material is fed by the screw member 18, it tends to pack around the member 19 and form a plug; which will serve the purpose mentioned.

This provision of'a plug or pack or perpetual cor so to speak of the material being handled may be secured by a variety of structures. I have just described one form'of such a structure.

At the lower right-hand portion of Figure 4 is another form in which the pipe or conveyor casing 161; has the choke or choked portion 22 at which point there is a break in the spiral screw. Similarly the choke in the pipe bore is obtained by having the pipe tapered or .stepped down to form a smaller passage either in the middle or at its end.

The formation of the compact body or plug of the material in its path of travel may be accomplished in still other ways.

At the lower right-hand portion of Figure 8 for instance, I have shown a spiral screw conveyor composed of the two sections 24 and 25 with their adjacent ends spaced from each other.

The spiral conveyor portion 25 which advances the material after it has passed the open space between the screw sections has closer spirals than the section 24. In other words, the linear distance parallel to the shaft between successive blade edges is less than the corresponding distance of that portion of the conveyor ahead of the compacting area. Material is thus carried away from the compacting area more slowly than it is brought to it. This will result in the formation of a plug or cork which will prevent the.

escape of vapors. The plug or cork may be provided for in a conveyor housing installed ver-,

tically or horizontally or at any desired angle. From the conveyor 20, the. material is dropped through a pipe 26 into the upright extraction chamber 27. The extraction chamber 27 is provided with a safety valve 27a.

I provide a gate valve 28 of suitable construc- In this pipe, I pref-.

tion by which the passage through the pipe 26 may be completely closed off if desired.

Since'the pipe 26 may be detachably connected with the conveyor above described and with the upright extraction chamber 27, it is obvious that the valve 28 affords "a means whereby the conveyor and the extractionchamber and the zones of their operations may, if necessary, be entirely shut oil. from each other.

For convenience, I have called the portion of the apparatus in which the material is carried from the hopper to the extraction chamber and in which the first plug or cork of material is formed the zone A. Likewise I have called the part of the apparatus now to be described and in which the material is first subjected to the action of the solvent the zone B.

; l Extractor with settling tank The extractor has the upright extraction chamber 27 already described and the main extraction chamber 29. The chamber 27 in the form of device here shown is in the shape of an upright cylinder and the extraction chamber 29, as here illustrated, is in the form of an inclined cylinder communicating at its lower end with the cham ber 27. The extractor has the drainage opening 27a controlled by a suitable valve, not shown.

It will, of course, be understood that the cross sectional shape of these chambers may be varied as circumstances may dictate.

Extended through the chamber 29 is a shaft 30. Journaled in suitable bearings. 0n the shaft 30 is a spiral conveyor 31. On the shaft 30 are also for the solvent extract mixture. Preferably arranged below this pipe and above the chamber 29 is the settling tank 34 having the inclined bottom 35 at the lowest point of which is a passage or pipe 36 leading to the main extraction chamber 29.

In the pipe 36 is a suitable gate valve 37 for eifectively closing the passage between the settling tank and the main extraction chamber..

'At the upper end of the settling tank 34 adjacent its shallowest part is a pipe 38 connecting the settling tank with the outlet pipe 33. Near the other end of the settling tank 34 and near the top thereof is a take-off pipe 39 which leads from the settling tank.

The outlet pipe 33 extends beyond the pipe 38 and connects with the pipe 39 as shown. The

pipe 33 is preferably provided with the safety valve 40.

From the pipes 33 and 39 leads a pipe 41 through a filter chamber 42 or the like containing pumice or other suitable coarse material or spe-' between the pipe 33 and the upright extraction chamber 27. There is also provided a valve 48 just beyond the pipe 38. A take-d pipe as leads from the lower part of the settling tank 36 and has a control valve .50. The take-oh pipe is is for taking off water or other material when it is not desirable to letsuch materials go into the main extraction chamber.

Referring to es 1 and 2, it will be observed that the solvent is furnished through a main supply pipe 51 and thence through branch pipes 52 through a plurality of openings to the'end of the extraction chamber 29, farthest from the material intake and closest to the egress conor replaced by access through the hole 54.

It will, of course, be understood that the apparatus is provided with suitable level gauges, pressure gauges, thermometers and so forth which need not here be particularly shown or explained. It should perhaps also be said that the extractor is jacketed for temperature control in ordinary ways not here shown.

In the extractor, the raw material being richest in extractable substance is immediately attacked by the relatively large excess of solvent. The fresh solvent on the other hand first meets the material from which most of the extractable substances have already been taken.

As the material is carried through the chamber 29, it i mechanically advanced and thoroughly agitated to efiect complete permeation of each particle by the solvent.

Theslight incline of the chamber 29 causes the solvent to fiow slowly counter-current to material being treated.

It will, of course, be understood that the solvent is supplied at a proper rate to suit the material being treated.

. Preferably, I provide short breaks 55 in the spiral conveyor blades for affording zones 0 tenacious permeation by the solvent.

The temperature of the extractor may be controlled through the jacket by use of the steam or cold water or otherwise.

The mixture of solvent and extractable substances flows out through the pipe 33. It will be obvious that since the material moves in one direction through the extractor and the solvent moves in the other direction, the

solvent will take up its fullest capacity of extractable substance, and will leave the apparatus when ratio of extractable substances to solvent is the highest commercially possible.

It will, of course. be understood that during the normal operation of the apparatus, the valves 47, 46, 44a and 45 are open and the valves 48, 44, and 3'7 are closed.

The settling tankis of special form, whereby the liquid with fine particles of the parent material enters at the shallow side, so that the particles are permitted to settle toward the deeper end of the tank.

The solvent extract mixture then flows through the pipe 39 and through the coarse filter 42 where elusive fine particles are trappedor where the solvent extract 1-1.1;

Thence the solvent extract mixture leaves the present apparatus.

When it is desired to discharge the contents of the settling tank into the main extraction charm her, this can be done by proper m. A It pulation oi the valve 3?.

I In completing the description of this portion of the apparatus, it may be well to say that the parts just described may be flushed and settlings removed by simple manipulation of the valves and solvent pump. First the level of the solvent in the connecting chambers 2? and 29 and the egress conveyor housing 57 is lowered sufliciently by pumping solvent out through the pipe 53 to the tank 59, equipped with vent pipe has, safety valve 59b. The valve dlis closed, the gate 37 is opened and the settling tank drains by gravity. Flushing is accomplished by pumping fresh solvent back through the coarse filter bed 42, thence through the settling tank, and thence to the main extraction chamber 29.

On resumption of the processing, the contents of the tank 59 are first returned to the extractor after which fresh solvent is again used.

Thus there is efiected the complete and thorough separation of fine particles from the solvent mixture before it goes to the stills for further treatment and grease recovery.

Furthermore fine particles of material are re-- turned immediately and without extra handling to the extractor where they belong and where they again become a part of the mass being extracted.

The solvent extract mixture is taken away from the apparatus in excellent condition and with a minimum of parent material.

' housing 57 by means of a spiral conveyor 60,

which dips into the chamber 29 far enough to provide for the removal of treated material at the same rate at which it is admitted, but not so fast as to interfere with the maintenance of a proper volume of material in the main e tion chamber.

Depth of the material in the extractor is governed by regulation of the conveyor speed in the main extraction chamber and by regulation of the dip of the conveyor 60 into the chamber 29.

The egress conveyor chamber 57 is long enough and at a. proper angle for affording proper conveyance of the material, and is high enough so that the solvent will not overflow its upper end.

The solvent is ordinarily maintained at a. level with the outlet pipe 33.

Substantially on a level with the pipe 33 or preferably just a little higher, an outlet pipe 61 leads from the conveyor housing 57 to the intake side of the solvent pump 56. This aflords continuous circulation and prevents stagnation of such solvent as flows upwardly in the egress conveyor housing and also handles any excessot the solvent which seeps back from the residue in the conveyor above the solvent level line, flowing this solvent by gravity to the solvent pump whence it is restored tothe extraction cycle.

Thus, and by further means now'described, a considerable amount of the solvent in the mate- 150 e is subjected to suitable inert bleaching terial.

being moved to be compressed for squeezing out a large part of the surplus solvent. As shown, the shaft 62 on which the spiral conveyor 60 is mounted has an enlargement 63 somewhat similar to the enlargement 19 already referred to,

but there is no break in the spiral conveyor 60.

Thus the enlargement 63 causes the material to be squeezed, while the spiral conveyor moves it along at -a uniform rate. Consequently, a large part of the surplus solvent is squeezed out, and it passes back through a by-pass pipe 64 at the side of the housing 57, shown in dotted lines in Figure 3.

From the upper end of the egress conveyor, the residue material drops through the pipe 64 to the conveyor housing 66. Suitably arranged in the pipe 65 is a gate valve 67, which may be closed in cases of emergencies, or whenever desired, for isolating the primary drier from the extractor. I r

At the upper end of the pipe 65 is a flush-inlet pipe 68 in which is a control valve 69. Connected with the flush-inlet pipe 68 is a branch 70 in which is a safety valve 71.

The conveyor housing 66 has a spiral 72 similar to the spiral 18 and 'a spiral 73 similar to the spiral 20 with an enlargement 74 on the shaft 75 similar to the enlargement 19 on the shaft 21. The purpose of this structure is to provide a choke orperpetual cork for the incoming end' of the primary drier.

' Primary drier The primary drier, so called because it is the first to which the residue is subjectedu nd because it takes out the largest proportion'of the solvent from the residue before the residue goes to the finishing driers described later, will now be explained.

This primary drier comprises a large rotary drum 76. This drum is journaled at one end on the pipe 77 and at the other end on the pipe 78. The pipe v77 forms a jacket for the conveyor housing 66 and is itself supported by a suitable standard 79. The pipe 78 is supported by a standard 30."

' The drum 76 has a steel jacket 81 The jacket and the exposed parts of the drum are preferably covered by asbestos and other insulating ma terial not here shown.

" The jacket 81 is provided with annular ribs 82 which travel on suitably mounted rollers 83 between guides 84.

on the jacket 81 is formed a gear 85 which meshes with a pinion 86 on'the line shaft 87 hereinafter referred to. I

'The pipe 77 is closed and sealed at its ends around the housing 66 as shown, and between it and the housing 66 is a passage 88.

On the inside of the primary drier, a pipe 89 connects with the passage 88 and on the outside of the drier the passage 88 is connected with vacuum take-off pipes 90 and 90a in which are suitable control valves 91.

The pipe 78 above referred to houses a spiral conveyor 92 on a hollow shaft 93, which projects from the closed ioumaled end 94 of the pipe 78. The hollow shaft 93 forms also a means for conducting heat or cold, which means is connected by use of a universal ball and socket joint 95 with a suitable heat or cold supply so in which shaped as shown in Figure '5. These scoops are is a control valve 97. In my apparatus, I have preferably coursed steam through the hollow shaft described.

At the inner end of the hollow shaft 93 is another ball and socket joint 98 through which steam flows into a four-way T-fitting 99 and thence through a plurality of steam conducting pipes 100. These pipes emerge through one end of the primary drier 76 by long threaded insertion through the drier and so as to engage other pipe fittings 101, which conduct steam to a steam jacket 81.

The pipes 102 in' the steam jacket are connected with an exhaust steam and condensation outlet pipe 103 which discharges into an annular sheet iron exhaust steam cage 104, clearly shown in Figure 4.

A drain pipe 105 leads from the bottom of the cage 104. In the pipe 103 is a control valve 106.

The conveyor housing 78 has a safety valve 107 and material is discharged by the conveyor 92 into an upright conveyor housing 16a. The material residue is carried into the primary-drier by means of the conveyor section 72. The enlargemnt 74 affords a plug which establishes a seal or cork in the intake end of the primary drier.

The rotation of the primary drier causes this residue to level out over the full length of the lower part of the drier where the residue is con- 1 tinually heated by the steam jacket. At what appearsln the drawings as the right-hand end of the primary drier, the material is dipped up in especially designed scoops 108' which are L- 110 rigidly secured in place in any suitable way and such bracing as is desired may be provided for them. 1

The fixed pipes 100 aflord conveying means for bracing the scoops.

The conveyor housing 78 within the primary drier is shaped to fit a wide receiving mouth 109.

As the drier rotates, the front side of the mouth of each scoop dips into the material and scoops it up and as the drier continues its travel, the con- 12o tents slide down the scoop bottom to the back and then slide along the back and are dropped into the conveyor housing mouth 109 "when the scoop approaches 180-from its loading point;

The material is carried along by the conveyor 92 and discharged into the conveyor housing 16a.

It will be understood that the volatile vapors released in the primary drier will be drawn off through the vacuum suction pipe 89.

The close proximity of the material to the live 1.30,

steam core of the conveyor shaft in the casing 78 increases the volatilizing of the solvent in the material and-makes advisable the installation of the safety valve 107.

The provision of the cork forming means 22 in m the casing 16a; establishes a seal at the outgoing end of the primary drier and insures maintenance of effective vacuum.

To take oil additional volatile vapors, I have provided a vacuum line 110 connected with the casing 78. In the line 110 is a suitable control valve 111.

Thus in the primary drier, extracted residue is freed from most of its contained solvent by means of an eflicient application of drier heat and adequate vacuum lines and in addition there is. provided a suitable and novel means for keeping the material in continuous motion toward the final driers. 1w

' veyed to the fixed d 112 by e conveyor 113 similar to the conveyor 13, 13, 2c, and 21, first above described and shown st the upper left-hand pe o of Figure l. v

The drum 112 is provided with o jcchet 11 1 end jacket and the exposed portions of the drum covered with asbestos or the like not shown; Within the jcchet 114 ere suitable steam pipes 13 to which steum cold for temperature conol is through c. pipe 113 and my be l on ofi through pipe ii? in eny ordinorywey. Lt the upper pert of the 1112, pipes 113 or connected vacuum bps for to s ed p n vapors. These pipes 113 are controlled by m-ens oi valves no.

the lower pert of the drum 112 is ngcd a longitudinal shaft 123 on which is. e spiral conveyor 121 for conveying the material along the bottom of the drum from the intake end to the discharge end.

On the sheit we are the 123.

A pipe, 123 leads from the lower end of the ch 112 farthest from the conveyor 113. The pipe 123 is controlled by a suitable gate valve 124. The pipe 123 discharges into a. suitable conveyor housing 125 in which are the spiral conveyor members 2% end already described, which are so shaped as to provide the formation of a. cork or plug in the housing 125.

lirom'the housing 125, the material is dischcrged into o. pipe 123. In the pipe 126 is a, gate valve 127'.

Final drier From the pipe 126 or the conveyor housing 16a es the case may be, the residue material is discharged to a transverse conveyor 128. The conveyor 123 has 9. spiral conveyor 129 with a shaft 130. At suitable points in the length of the conveyor 123, material is discharged through ipes 131 inwhich ore gate valves 132 similar to those already mentioned.

The pipes 131 discharge into a. conveyor housing 66:; similar to the conveyor housing 66 in Figure 4. In the conveyor housing 661; is a. conveyor similar to that in the housing 66. Surroung a portion of the housing 66a is a, pipe 77a similar to the pipe '17 having outlet pipes 902: end 900 corresponding to the pipes and 300;. In the pipes 361) and 900 are control valves 91c similar to the valves 91. A pipe 89a enters the pipe 77a inside the drier and, volatile vapors are drawn off in a. or similar to that in vacuum suction'pipe 89. g

The final drier drum 133 is journaled on the pipe 77a in" the same manner that the drum 76 is journaled on the pipe 77. The drum 133- has a steam jacket 134 similar to the jacket 81.

This steam jacket 134 is suitably mounted for rotation and supported for instance in the same manner as the steam jacket 81 of the drum 76.

The end of the drum 133 opposite the intake end thereof however is difierently constructed from the corresponding end of the drum '16. This last-mentioned end has a, reinforced central portion 135 through which extends a pipe 136 for with a. suitable supply pipe 138 and a control valve 138a therein The end portion 135 is not only thickened on its side within the drum, but it is hollowed out axially end affords c plurality of outlets to sccoodete pipes 1 12 leading to the steam jacket. 4

Projected into the chamber portion of the end portion 135 end journuled therein is e sleeve 139, the'outer end oi which is closed round the pipe 136 as at 1420. The sleevelde curries ordi= new live steam supplied to it through a pipe 141.

. From the sleeve 133, the live steam enters the chamber portion. of the end portion 135 and is supplied through pipes 142 to the steam jacket 13%. At 143,1 have indicated e. door for the 133'. This door is shown somewhat diagremmeti colly, but in the ectuel drum, which I use, the construction is somewhat more elaborate so that a. tight joint is efiorded end the door may be easily removable and replaceable.

in this description, i shall refer to the pipe 136 as g dry or superheated steam pipe, which connects at its inner end with a plurality of branches 13 i radieting' fenwise downwardly and couniceting in turn at their lower ends with perforated pipes 145 extending lengthwise of the interior of "the finel drier and suitably rigidly inchored in place by means of supporting clamps The hot dry steam is supplied to the interior of the final drier end suitably rigidly anchored in place by means of supporting clamps 146.

The hot dry steam is supplied to the interior of the final drier and intimate contact with residue being dried through the perforations of the pipes 14.5.

The volatile vapors are drawn off through the gipe 89a, thence out through the pipes 902) and The final residue of parent materiel thoroughly dried and freed from all remaining traces of solvent may then be taken out after removing or opening the doors 143.

Ordinarily I will use about three final driers' for one primary drier.

The parts may be operated by suitable mechanism provided for the purpose.

I have shown in the drawings the line or power shaft 87 already referred to, which may be operated from any suitable source of power. At one end, the shaft 87 has a sprocket 147 aligned with a. sprocket 148 on the conveyor shaft 21. A chain 149 travels on the sprockets 147 and 148 for imparting rotation from the shaft 8? to the shaft 41.

Suitable gearing means 150 and 150a is provided for transmitting power from the shaft 87 to the shaft 31.

On the shaft 62 is a beveled gear 151 which is connected by a suitable chain of gearing mechanism 152 with the power shaft 87.

It should be understood that the shaft 75 is operated from the shaft 87 by suitable gearing means not herein particularly described or explained.

In Figure 1 at the place where the egress conveyor housing 5'7 joins the end of the chamber 29, a four-way T 158 is installed. On one side 93. Similarly I have shown in Figure 8 a gearing mechanism 154 for connecting the shaft 87 with the shaft 120.

It will be understood that I have not fully attempted to show the details of the gearing mechanisms and that suitable control and clutch means are provided so that the various operative parts may be thrown out of gear or into gear and properly controlled as may be desired.

Method of operation I will now briefly outline the method used with my apparatus and in this way explain the progress of the material through the apparatus.

The material in the hopper 10 may be separated from the conveyor just below the hopper by means of the valve 12 and the flow of mateial from the hopper may be controlled by that valve.

From the hopper, the material is discharged into the conveyor where it is acted upon by the members 18 and 20 and carried to the point of dischargev into the upright extraction chamber. The member 19 serves to cause the plug or cork of which explanation has been made and loss of vapors from the extraction chamber is thus prevented.

It should perhaps be mentioned in this connection that the edge of the conveyor member 20 has saw teeth 20a as indicated in Figure 1, where that conveyor member first acts on the packed material. This breaks up the material and preventsfeeding it in lumps or chunks to the extraction chamber.

The extractor may be isolated from the conveyor above it by means of the valve 28 as already explained.

Solvent is supplied to the extractor through the plural openings as above mentioned.

The'material drops into the upper end of the upright chamber 27 into a body of solvent and settles to the bottom and is then advanced by the conveyor 31 through the inclined chamber 29.

It should be understood that when the apparatus is operating, a substantial body of solvent is maintained in the upright chamber 27.

Material is carried along the inclining chamber 29and is thoroughly mixed and agitated to insure the complete permeation of the material by the solvent.

Since the fresh solvent and the extract-laden solvent travel in a direction opposite to the travel of the'material, it will be obvious that'the fresh solvent first attacks the material from which most of the extractable substances have been removed and the fresh material drops into solvent, Which is already laden with extractable extractable substances is immediately removed and so the solvent goes to the outlet pipe .33 carrying a maximum amount of such substances.

From the chamber 29, the egress conveyor removes the residue from the chamber 29 and discharges it to the conveyor 66, which carries it to the primary drier.

Particular attention is called to the fact that the construction and operation ofthe egress conveyor is such that the residue is removed with a minimum loss of motion, heat and solvent. The structure of the conveyor is such as to accomplish two very desirable results. In the first place, it affords opportunity for maximum action of the solvent on residue material Just before it leaves hot steam in the hollow conveyor shaft 93.

- ing 57 with the outgoing material to the return pipe 61, from which it enters the intake sideof the solvent pump and is restored to the main extraction cycle.

, Whereas the main extraction cycle provides counter-current -movement of solvent against material being treated when the residue moves up the inclined conveyor 57, the direction of solvent and material is concurrent.

Hence just before the material leaves the solvent, it is tenaciously attacked by fresh solvent and every trace of extractable substance procurable is obtained.

Then on emerging above the solvent level line, material is subjected to the special squeezing action as shown in Figure 3 at 63.

The excess of solvent flows back through the by-pass 61 and is conveniently restored to the Y extraction cycle again.

The extractor may be wholly separated from the primary drier by means of the valve 67.

It will of course be clear that by means of the valve 67 and the valve 28, the extractor as a unit can be cut out of the apparatus so far as the cycles of operation are concerned.

From the egress conveyor the material is discharged to the conveyor housing 66 shown in Figure 4 or the housing 113 shown in Figure 8, depending upon which type of primary drier is used.

Using the type of drier shown in Figure for the purpose of this explanation, it will be seen 115 that the material is dropped into the drum 76 at one end thereof and will tend to level itself out along the lower part of the drum as the drum rotates.

The material is subjected to heat from the steam jacket and of course the volatile vapors given of! are drawn off through the pipe 90.

The material which travels to the right-hand end of the drum as shown in Figure 4 is dipped up by the scoops 108 and dropped into the open mouth of the conveyor housing 78.

The conveyor 92 moves the material to the pipe 16a.

It is noted that there is a vacuum pipe 110 through which vapors may be drawn from the 180 discharge end of the conveyor housing 78. This is important because of the fact that during the progress of the material through the housing 78, it has been subjected to the heating action of the By means of the valves 67 and 124a, the primary drier may be cut off fromthe rest of the apparatus.

Thematerial is packed during its incoming movement to the primary drier and also during its passage away from the primary drier so that vacuum may be effectively maintained within the drier.

From the pipe or housing 16a, the material is discharged into the transverse conveyor 128 and from thence as already explained to the respective final driers, which become essentially batch drier-s holding measured charges of material for final treatment.

In the final drier, the material is subjected The final driers are preferably arranged in batteries so that material can be supplied to one of them and then this drier can be isolated from the rest of the apparatus by means of the valve 132 and the material can then be supplied to the adjacent final drier. There are a number of advantages in the structure of the final drier as heretofore described. I now refer particularly to the arrangement for supplying steam to the interior of the drier drum.

It is obvious that this means can be used for. supplying dry steam, wet steam, water, or any substance which may be introduced to the residue for purposes not here detailed. For instance, it might be desired under some circumstances and with some materials to rotate the drum to position where the pipes 145 were at the top, and then to allow a certain amount of water to trickle out and down through the body of material being dried for thus building up to a desired moisture content.

From the final drier the material is takenout free of any solvent, and can then be used for any available purpose.

It will, of course, be understood that a great many changes might be made in the construction of the various parts of my improved apparatus, in thesizes of materials used, proportions, as

well as in the arrangement of'elements and of parts with relation to each other, and it is my purpose to cover by my claims any such modifications or variations in structure which may reasonably come within the real scope of my invention and such claims.

I claim as my invention:

1. In a solvent extraction apparatus, .an extraction chamber, means for conveying material therethrpugh in' one direction and means for causing solvent flow therethrough in an opposite direction, a conveyor for removing material from the discharge end of the extraction chamber,

means for causing solvent flow in said conveyor in the direction of movement of material therein, means for withdrawing solvent from the, conveyor at a height above the extraction chamber,

and means for squeezing solvent from the ma- ,terial in the conveyor above the point of solvent removal therefrom.

2. In a solvent extraction apparatus, an upwardly inclined extraction chamber, means for conveying material therethrough in one direction and means. for causing solvent flow therethrough in an opposite direction, a conveyor for removing material from the discharge end of the extraction chamber, means for causing solvent flow in said conveyor in the direction of movement of material therein, and means including a .pump for taking the solvent from the upper level thereof in the conveyor and returning it to the extraction chamber at a point near the entrance to the conveyor.

\ 3. In a solvent extraction apparatus, an upwardly inclined extraction chamber, means for conveying material therethrough in one direction and means for causing solvent flow therethrough in an opposite direction, a conveyor for removing material from the discharge end of the extraction chamber, means for causing solvent flow in said conveyor in the direction of movement of material therein, means for taking the charge,

eluding a tank, the pump and piping, whereby the solvent from the upper'level thereof in the conveyor and returning it to the extracting cham- -means for conducting the mixture of solvent extract substancesand 'fineparticles of material being treated to the upper part of the settling tank near one end thereof, and means for conducting the clearer supernatant liquid from the tank near its other end, a filter of coarse particles through which the liquid is then passed, a safety valve, and a suitable connection to a vacuum pump for pressure relief, both connected with the last-named means.

5. In a solvent extraction apparatus, an upright extraction chamber having an outlet near J its top for solvent extract mixture, a second extraction chamber inclined upwardly from the bottom of the first chamber, means for conveying material from the bottom of the first chamber through the second chamber, means for taking the material from the second chamber, means for pumping solvent to the second chamber near its discharge en means for conveying raw material to the upper end of the upright chamber, a settling tank for receiving solvent extract mixture from said outlet in the first chamber and adapted to discharge settlings directly into the second chamber, a valve for controlling such dismeans for flushing the settling tank inpump lowers the solvent level sufllciently in the first and second chambers by pumping solvent into the tank, so that the entire volume of material inthe settling tank gravitates to the second extraction chamber and whereby said pump flushes the settling tank by use of new solvent.

6. A method of solvent extraction comprising moving a body of material through a body of counter-currently moving solvent and then conveying the material from the main portion of said body of solvent upwardly through a separate passage and subjecting the residue material in said passage just prior to the emergence above the solvent level to a final intensive treatment by fresh solvent moving concurrent with the material, squeezing liquid from the material after it is above the solvent level, and returning solvent from the solvent level in the passage to the main extraction cycle.

'7. The continuous method of solvent extraction comprising the moving of material through a-body of counter-currently moving solvent, then conducting the material upwardly from the body of solvent with aconcurrent movement of material and fresh solvent, squeezing the liquid from the material after it leaves the solvent level, continuing the conveyance of material beyond the squeezing area to a drier, subjecting the material in such a drier simultaneously to heat and agitation, removing the material from the drier and conveying it to a final drier and there subjecting it to agitation, heat and the direct action of suitable chemicals including superheated steam.

WALTER. E. FLUMERFELT. 

